For example, a semiconductor element such as a switching element or a diode is used in a circuit such as a switching power supply or an inverter. These semiconductor elements require a high breakdown voltage and a low on-resistance. A relation between the breakdown voltage and the on-resistance is a trade-off relation depending on a semiconductor material.
Due to the progress of the technological development, a semiconductor element which has a low on-resistance in the vicinity of a limit of a main semiconductor material silicon has been realized. In order to improve the breakdown voltage further or reduce the on-resistance further, it is necessary to change the semiconductor material. It is possible to improve the trade-off relation depending on a semiconductor material and to realize high breakdown voltage and low on-resistance by using a GaN-based semiconductor such as GaN or AlGaN, or a wide bandgap semiconductor such as silicon carbide (SiC) as a semiconductor material of a switching element.